Result
Caused by: org.apache.solr.common.SolrException: Invalid Date String:'Mon Sep 14 01:48:38 CEST 2015'
at org.apache.solr.util.DateFormatUtil.parseMath(DateFormatUtil.java:87)
at org.apache.solr.schema.TrieField.readableToIndexed(TrieField.java:473)
at org.apache.solr.schema.TrieField.createFields(TrieField.java:715)
at org.apache.solr.update.DocumentBuilder.addField(DocumentBuilder.java:48)
at org.apache.solr.update.DocumentBuilder.toDocument(DocumentBuilder.java:123)
at org.apache.solr.update.AddUpdateCommand.getLuceneDocument(AddUpdateCommand.java:83)
at org.apache.solr.update.DirectUpdateHandler2.addDoc0(DirectUpdateHandler2.java:237)
at org.apache.solr.update.DirectUpdateHandler2.addDoc(DirectUpdateHandler2.java:163)
at org.apache.solr.update.processor.RunUpdateProcessor.processAdd(RunUpdateProcessorFactory.java:69)
at org.apache.solr.update.processor.UpdateRequestProcessor.processAdd(UpdateRequestProcessor.java:51)
at org.apache.solr.update.processor.DistributedUpdateProcessor.doLocalAdd(DistributedUpdateProcessor.java:955)
at org.apache.solr.update.processor.DistributedUpdateProcessor.versionAdd(DistributedUpdateProcessor.java:1110)
at org.apache.solr.update.processor.DistributedUpdateProcessor.processAdd(DistributedUpdateProcessor.java:706)
at org.apache.solr.update.processor.LogUpdateProcessor.processAdd(LogUpdateProcessorFactory.java:104)
at org.apache.solr.update.processor.UpdateRequestProcessor.processAdd(UpdateRequestProcessor.java:51)
at org.apache.solr.update.processor.LanguageIdentifierUpdateProcessor.processAdd(LanguageIdentifierUpdateProcessor.java:207)
at org.apache.solr.handler.loader.XMLLoader.processUpdate(XMLLoader.java:250)
at org.apache.solr.handler.loader.XMLLoader.load(XMLLoader.java:177)
at org.apache.solr.handler.UpdateRequestHandler$1.load(UpdateRequestHandler.java:98)
at org.apache.solr.handler.ContentStreamHandlerBase.handleRequestBody(ContentStreamHandlerBase.java:74)
at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:143)
at org.apache.solr.core.SolrCore.execute(SolrCore.java:2068)
at org.apache.solr.client.solrj.embedded.EmbeddedSolrServer.request(EmbeddedSolrServer.java:179)
at org.apache.solr.client.solrj.SolrRequest.process(SolrRequest.java:135)
at org.apache.solr.client.solrj.SolrClient.add(SolrClient.java:174)
at org.apache.solr.client.solrj.SolrClient.add(SolrClient.java:191)

P.S. the line "solr.update" takes care to create a partial update document, with proper